The invention relates to a device according to the precharacterizing clause of claim 1 and to a method according to the precharacterizing clause of claim 7.
A device of the genre and a method of the genre are known from U.S. Pat. No. 5,877,455, whereby the sensors in each case must be on all the axles of the vehicle and, if applicable, of a trailer. From DE 36 11 189 A1 and from DE 195 08 239 A1 are known devices and methods not of the genre.
As with many other differently designed devices and methods known in practice, the mentioned documents deal with weighing equipment by aid of which the load capacity of a utility vehicle is supposed to be precisely ascertained and thus determined.
The component assuming the payload, as known from DE 36 11 189 A1, can, for example be the flatbed body of a truck or a container or, as known from DE 195 08 239 A1, the trailer of a semitrailer truck or, as often in practice, the scoop of a front-end loader, the dump body of a dump truck or of a dumper.
The striven-for most precise possible weight determination, according to DE 36 11 189 A1, serves to maintain the legally prescribed maximum weight of the payload and/or the maximum weight of the vehicle and promotes, through application of several sensors arranged in a distributed manner, the monitoring of a uniform distribution of the load material. According to DE 195 08 239 A1, the weight of a trailer is supposed to be able to be measured during travel, without taking into consideration the transfer of force between the tractor and the trailer. Furthermore, in operation the most precise possible determination of the weight of the payload is especially desired for the purpose of accounting; it can, however, also serve the forming of conclusions on the wear on the vehicle. With the arrangement according to U.S. Pat. No. 5,877,455 the acceleration behavior of the axles on which the acceleration sensors are arranged is strongly influenced by the spring behavior of the tires. Different air pressures in the tires as well as different deformations of the tires can thus influence the measurement results. The air pressure in the tires is influenced by the temperature of the tires, this again through ambient temperature, sunshine as well as travel duration and travel speed. The deformation of the tires is influenced by the tread pattern strength as well by through the age of the tires.
It is desirable, beyond just the registration of the amount that is being transported by the vehicle, to also give evidence as to whether the vehicle is traveling in an unloaded or a loaded condition. This kind of information is used by the design engineer in the dimensioning of the vehicles and by the owner of the vehicle in the choice of the tires best suited for the load at the time. In addition, the information can allow, for example especially with rental vehicles, evidence about whether an impermissibly long stretch is covered with an impermissible load or whether in general a prescribed maximum loading has been exceeded, for example, depending on the unevenness of the ground, whether a specific maximum weight was contained. Furthermore, through a supplementary weight determination, a distinction can be made between the pausing and loading time, so that operational events can be optimized.
With the known arrangements there is a disadvantage in that the evidence about the present weight can be obtained usually only in a certain weighing position of the component assuming the payload, for example in a certain tipping position of the selected dumping body. This holds true, for example, for conventional weighing rods which are provided with strain gauges and which evaluate a torsion or a bending of the weighing rods. However, in the rest condition of the component assuming the payload, if this component is not tipped no evidence can be gathered on the load weight of the vehicle. Depending on the tilt state of the vehicle during the weighing, the weight determination can be erroneous, so that false weight data can inadvertently or, in the case of rental vehicles, intentionally result.
Other measuring methods are independent of a particular weighing position of the component assuming the payload. Such systems, which for example evaluate the hydraulic pressure on the piston with which the component is raised, yield usable measurement results, however, only when the component under consideration at the time is raised. In the rest condition of this component, if the hydraulic piston is not activated no evidence concerning the load weight of the vehicle can be obtained.
Furthermore, measurement methods are known in which the pressure in oil- or gas-filled springs and shock absorbing elements of the vehicle can be determined. These methods are independent of a particular weighing position and can also work in the rest condition of the component assuming the payload. The disadvantage, however, is their complicated construction and the required special adapting to the multiplicity of different vehicle types. The measurement accuracy can be interfered with by the raised friction inside the spring elements, if the spring elements are provided in a slanted position with respect to the vertical or the vehicle is positioned on steep ground. Also, different frictional values result inside such (MacPherson) struts due to temperature influences, so that in the course of the day, with changing ambient temperatures or depending on the sunshine, different measurement values are obtained for the same payload and the weight indications are correspondingly inaccurate.
The object of the invention is, proceeding from a generic arrangement, to improve the arrangement so that it makes possible the obtaining of evidence concerning the load condition of the vehicle with the vehicle standing still, the arrangement being applicable in a cost-effective way to a multiplicity of different vehicles, as well as to specify a suitable process for this.